Process for preventing stains in photographic color material by treatment with basic acids immediately prior to drying



Patented July 11, 1950 UNITED STATES PATENT OFFICE,

2,515,121 PROCESS FOR PREVENTING STAINS IN PHO- TOGEAPHIC COLOR MATERIAL'BY TREAT- MEN T WITH BASIC ACIDS IMMEDIATELY PRIOR TO DRYING Harold C. Harsh and James E. Bates, Binghamton,'N. Y., a'ssignors to General Aniline Fllm Gorporation, New York, N. 'Y., a-corporation of Delaware No Drawing. Application Novembers, 1945,

Serial No. 627,534

11 Claims.

This invention relates to photographic antistain baths, to anti-stain baths employed in multi-color photography, and especially tononstaining baths for the washing of multi-color photographic materialfollowing the fixing treathal'ides in all the layers are reduced to metallic silver. After the second developmenuthe mate- 'rial is cleared in running water, hardened in an aqueous solution consisting of either chrome or potassium alum, and then washed in running water. After the latter treatment, the silver ipresent'in all the layers formed during the first and second development is converted into a salt byany of the known silver-salt formers, commonlyknown as bleaching baths, and the silver salt thus formed is .then removed by dissolving it ina silver-salt solvent such as, for example, hypo. The .material is then washed for a long period of time and then dried.

.Prior to the final washing operation it is essential that .the residual second or color developer .andibleach solutions be removed, otherwise stains Will'be formed during the drying operation, which are particularly noticeable in the White area. In orderto prevent this staining, an extended Washingtime inrunning water of from fifteen minutes to two hours, has been proposed. Even if this proposal be adopted, stains are nevertheless formed after the drying operation. It is believed that the staining results from the oxidation of traces of the color developer retained in the layers of the material following color-forming development, which then react with the unused color-former.

An object of the present invention is to elimimulti-= color photographicmaterial in a shorttim'e while avoiding staining.

Other objects and featuresof the invention-will become more apparent as the description pro ceeds.

We "have found that'the above objects are accomplished by employing, as a final rinse bath, an aqueous solution containing a small quantity of a weak acid which maybe a water-soluble organic acidpreferably those containing from 1 to 6 carbon atoms, such as, for example, formic acid, acetic acid, acryli cacid, citric acid, m'aleic acid,

mal'onic-acid, glutaric acid, oxalic acid, tartaric acid, or an'inorganic acid such as boric acidand the like. The concentration of the water-soluble weal; acid may vary from as little as 0.01 to 1%. Amounts higher than 1 give little improvement in stain prevention from a practical standpoint and, accordingly, concentrations ranging from between-0.05% to 0.5% are most desirable.

The-photographic multi-layer materials, which may be processed with the anti-stain bath of the present invention, arecolor reversible film, color negative film, color reversible printing material coated on a white opaque base, and color positive printing material coated on paper, irrespective of whether-the .dyestuff images are produced with color-formers present in the emulsion or by a selective second exposure followed by color development. The-color reversible film consists of an integral tripack emulsion coated on the usual clear cellulose acetate or nitrate film base. Each of the emulsions are sensitized to one-of the pri 'mary colors of light; namely, blue, green, and flBC l. The top layer is blue sensitive. A filter layer,

yellow in color and blue absorbing, lies under-the top layer. Below this filter layer, lies a green sensitive emulsion layer, and below this is a red sensitive emulsion layer. 'Each of the three silver-halide emulsion layers contain dye-forming compounds which unite during the development of silver image in an aromatic amine developing agent to form a dye with the oxidation product of the developing agent, or may be free from color-formers, inwhich case the film is processed with'the color-formers in the color developers by "the selective second exposure and color develop-v ment method as described in United States Patents 1,897,866; 1,900,870; 1,928,709 and 1,980,941; The color negative film is made up in the same manner as the color reversible film, with there! ception that it may contain a layer of clear gelatin between the red sensitive layer and the green sensitive layer. The color reversible white opaque material is prepared in the same manner as color reversible film and the color negative film, with the exception that the base consists of an opaque white film. The color paper is also constructed in the same manner as the color reversible film and the color negative film, with the exception that the emulsion is coated on a baryta coated paper base.

As silver is formed during development, it must be removed after color development by treatment in a bleach, followed by treatment in a bath of sodium thiosulfate according to usual practice. A yellow dye is formed in the blue sensitive emulsion; a magenta dye is formed in the green sensitive emulsion; and a cyan dye is formed in the red sensitive emulsion. Combinations of these three printing primaries will produce all of the other colors in the finished film or print. Suitable methods for the preparation of photographic multi-layer materials have been described in the literature relating to color photography, and are, therefore, not described here.

The following examples describe in detail methods for accomplishing the above objects, but it is to be understood that they are inserted merely for purposes of illustration and are not to be construed as limiting the scope of the invention.

Example I Grams p-Monomethylamine-m-phenol sulfate 3 Sodium sulfite 50 Hydroquinone 6 Sodium carbonate (monohydrate) 40 Sodium thiocyanate 2 Potassium bromide 2 Water, to make up l liter Short stopped for 3 minutes at 68 F., in a 5% aqueous solution of sodium bisulfite.

- Washed for 2 minutes in running water at 68F.

Color developed for minutes at 68 F., in a developer of the following composition:

- Grams p-Aminodiethylaniline HCl 4 Sodium sulfite 5 Hydroxylamine HCl 2 Sodium carbonate 40 Potassium bromide 1 Water, to make up 1 liter Rinsed for 4 minutes in running water at H Grams Di-potassium mono-sodium ferricyanide 100 Potassium bromide 15 Disodium phosphate 40 Sodium bisulfate 25 Water, to make up 1 liter Grams Hypo 200 Borax 10 Water, to make up 1 liter After fixing, the material was washed for 10 minutes in running water at 68 F.

' After the final wash, one print was allowed to dry while the other was rinsed for 2 minutes in a 0.1% solution of acetic acid and then allowed to dry. At this point, the prints appeared identical. After normal drying, the print rinsed in the acetic acid solution showed brighter colors and more brilliant highlights than the print given only a water wash for 15-20 minutes.

When the drying was carried out under conditions of high humidity so that the drying time was extended for several hours, the water rinsed print showed even greater highlight stains while the print rinsed in acetic acid solution did not change.

. Example II Example I was repeated with the exception that the colored photographic multi-layer material employed was color paper and the final rinse bath was a 0.1% solution of citric acid instead of a 0.1% solution of acetic acid. The color print washed in water showed objectionable stains after drying, while the print treated with the solution of citric acid was clear and unstained.

Example III Example I was repeated with the exception that the final rinse bath was a .Ol% solution of oxalic acid instead of a 0.1% solution of acetic acid. After fixing and washing, the color print rinsed in plain water showed objectionable stains, while the print treated with the oxalic acid solution was clear and unstained.

' From the above examples it is manifest that the multilayer photographic material rinsed in plain water shows marked staining upon drying of said material. This staining occurs especially under slow drying conditions and is probably due to the coupling of the slow oxidation product of the color developer with a residual colorcoupler present in one or more layers.

In place of the water soluble organic acids referred to above, boric acid, in'the same concentration, may also be employed.

The above specific examples are to be regarded as merely illustrative of the invention, and not in any sense restrictive. It will be obviousto anyone skilled in the art that many modifications such as substituting equivalent material and varying the proportions of materials used are within the spirit and scope of the invention as defined in the appended claims.

We claim:

1. In a process of color photography the method of preventing stains on color images selected from the class consisting of indophenol and azomethine dyes produced in multilayer color film by color-forming development which comprises washing said film after exposure, color development, bleaching, and fixing, but prior to drying with an aqueous solution consisting of water and a weak acid selected from the class consisting of Water-soluble open chain mono-, diand tribasic acids.

1 2. The process according to claim 1, wherein the said water-soluble open chain mono-, di-, and tribasic acids contain from 1 to 6 carbon atoms.

3. In a process of color photography the method of preventing stains on color images selected from the class consisting of indophenol and azomethine dyes produced in multilayer color film by color-forming development which comprises washing said film after exposure, color development, bleaching, and fixing, but prior to drying with an aqueous solution consisting of water and acetic acid.

4. In a process of color photography the method of preventing stains on color images selected from the class consisting of indophenol and azomethine dyes produced in multilayer color film by color-forming development which comprises washing said film after exposure, color development, bleaching, and fixing, but prior to drying with an aqueous solution consisting of water and citric acid.

5. In a process of color photography the method of preventing stains on color images selected from the class consisting of indophenol and azomethine dyes produced in multilayer color film by color-forming development which comprises washing said film after exposure, color development, ibleaching, and fixing, but prior to drying with an aqueous solution consisting of water and oxalic acid.

6. The method according to claim 1 wherein the concentration of the said water-soluble open chain mono-, di-, and tribasic acid ranges from .01% to 1%.

7. In the process of producing color photographic images selected from the class consisting of indophenol and azomethine dyes in a multilayer color film by exposing the film, color-form ing developing the same, bleaching, fixing and washing, the improvement which comprises avoiding the formation of stain, after the bleaching, fixing, and washing operation, by rinsing the film with an aqueous solution consisting of water and a weak acid selected from the class consisting of water-soluble open chain mono-, diand tribasic acids.

8. The process according to claim 7, wherein the said water-soluble open chain mono-, di-, and tribasic acids contain from 1 to 6 carbon atoms.

9. In a process of producing color photographic images selected from the class consisting of indophenol and azomethine dyes in a multilayer color film by exposing the film, color-forming developing the same, bleaching, fixing and washing, the improvement which comprises avoiding the formation of stain, after the bleaching, fixing, and washing operation, by rinsing the film with an aqueous solution consisting of water and acetic acid.

10. In a process of producing color photographic images selected from the class consisting of indophenol and azomethine dyes in a multilayer color film by exposing the film, colorforming developing the same, bleaching, fixing and washing, the improvement which comprises avoiding the formation of stain, after the bleaching, fixing, and washing operation, by rinsing the film with an aqueous solution consisting of water and citric acid.

11. In a process of producing color photographic images select-ed from the class consisting of indophenol and azomethine dyes in amultilayer color film by exposing the film, color-forming developing the same, bleaching, fixing and. washing, the improvement which comprises avoiding the formation of stain, after the bleaching, fixing, and washing operation, by rinsing the film with an aqeuous solution consisting of water and oxalic acid.

HAROLD C. HARSH. JAMES E. BATES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,753,059 Murray Apr. 1, 1930 1,930,140 Becker Oct. 10, 1933 1,981,391 Russell Nov. 20, 1934 2,134,266 Sanders-Dolgoruki Oct. 25, 1938 2,203,903 I-Iam June 11, 1940 2,238,495 Mannes Apr. 15, 1941 2,280,721 Schilling Apr. 21, 1942 2,323,481 McQueen July 6, 1943 2,367,516 Muehler et al. Jan. 16, 1945 2,367,548 Vittum Jan. 16, 1945 2,384,658 Vittum Sept. 11, 1945 2,414,491 Tulagin Jan. 21, 1947 

1. IN A PROCESS OF COLOR PHOTOGRAPHY THE METHOD OF PREVENTING STAINS ON COLOR IMAGES SELECTED FROM THE CLASS CONSISTING OF INDOPHENOL AND AZOMETHINE DYES PRODUCED IN MULTILAYER COLOR FILM BY COLOR-FORMING DEVELOPMENT WHICH COMPRISES WASHING SAID FILM AFTER EXPOSURE, COLOR DEVELOPMENT, BLEACHING, AND FIXING, BUT PRIOR TO DRYING WITH AN AQUEOUS SOLUTION CONSISTING OF WATER AND A WEAK ACID SELECTED FROM THE CLASS CONSISTING OF WATER-SOLUBLE OPEN CHAIN MONO-, DI- AND TRIBASIC ACIDS. 